LONDON, April 15 (Reuters) - Russia has deliberately pushed Ukraine "to the brink" in recent days and increased the risk of violent confrontation there, British Foreign Secretary William Hague will say on Tuesday in a speech in London.

Hague's comments, released in advance by his office, come after Russia declared Ukraine to be on the verge of civil war and as Kiev said an "anti-terrorist operation" against pro-Moscow separatists was under way.

"In recent days Russia has deliberately pushed Ukraine to the brink, and created a still greater risk of violent confrontation," Hague will say, according to the extracts.

Britain is ready to support other European countries which are "vulnerable to the pressure of creeping oligarchisation", he will say, a reference to wealthy Kremlin-backed businessmen buying up strategic assets abroad.

"Russia's behaviour has laid bare the danger of the creation of concentrations of Russian economic, political and media power that subvert democratic institutions, particularly in South-Eastern Europe," he will say.

Russia's actions in Ukraine will strengthen the "unity, relevance and common purpose" of the NATO western military alliance, he will add, and bolster the case for increased defence spending among allies whose defence outlay had slipped below its guideline levels. (Reporting by William James and Andrew Osborn; Editing by Andrew Osborn)